9 Most VSAQ’s of Cell Cycle and Cell Division Chapter in Inter 1st Year Botany (TS/AP)

2 Marks

VSAQ-1 : Among prokaryotes and eukaryotes, which one has a shorter duration of cell cycle?

Prokaryotes have a shorter cell cycle duration compared to eukaryotes.

  1. In prokaryotes, such as bacteria, the cell cycle can be relatively rapid, taking as little as 20 minutes to complete a full cycle, including replication and division.
  2. In contrast, eukaryotes, including animal and plant cells, have a longer cell cycle, which typically spans approximately 24 hours or more, depending on the cell type and organism.

VSAQ-2 : Which of the phases of cell cycle is of longest duration?

G1 (Gap 1) Phase is typically the longest duration phase of the cell cycle in eukaryotic cells. This phase involves cell growth, protein synthesis, and preparation for DNA replication. The duration of the G1 phase can vary among different cell types and organisms, but it is generally the longest phase in the cell cycle.

VSAQ-3 : Which tissue of animals and plants exhibits meiosis?

  1. In animals, meiosis occurs in the germ cells (sperm and egg cells) to produce haploid gametes.
  2. In plants, meiosis takes place in specialized structures known as sporangia or spore cases. These structures are often found in reproductive organs like the sporophylls of ferns, anthers and ovaries of angiosperms (flowering plants), and cones of gymnosperms. Meiosis in plants produces haploid spores, which eventually give rise to gametophytes.

VSAQ-4 : Given that the average duplication time of E.coli is 20 minutes. How much time will two E.coli cells take to become 32 cells?

Two E. coli cells will indeed take 80 minutes to become 32 cells, given an average duplication time of 20 minutes. This is because each generation doubles the number of cells, and to reach 32 cells, you need four generations, each taking 20 minutes. Well explained!

VSAQ-5 : Which of the four chromatids of a bivalent at prophase-I of meiosis can involve in cross over?

During prophase I of meiosis, non-sister chromatids of a bivalent (a pair of homologous chromosomes) can indeed undergo a crossover event. This crossover occurs between homologous chromosomes, and it involves the exchange of sections of non-sister chromatids. This process, also known as genetic recombination or crossing over, leads to the shuffling of genetic material between homologous chromosomes, resulting in increased genetic diversity in the resulting gametes.

VSAQ-6 : If a tissue has at a given time 1024 cells. How many cycles of mitosis had the original parental single cell undergone?

If there are 1024 cells in a tissue at a given time, it means the original parental single cell had undergone 10 cycles of mitosis. This is because the number of cells doubles after each mitotic cycle, and 2^10 (2 raised to the power of 10) equals 1024.

VSAQ-7 : An anther has 1200 pollen grains. How many pollen mother cells must have been there to produce them?

To produce 1200 pollen grains, there must have been 300 pollen mother cells because each pollen mother cell undergoes meiosis to produce four pollen grains. Therefore, 1200 pollen grains would result from 300 pollen mother cells.

VSAQ-8 : At what stage of cell cycle does DNA synthesis occur?

DNA synthesis occurs during the S-phase (Synthesis phase) of the cell cycle. This phase is a part of the interphase and is characterized by the replication of the cell’s DNA. During the S-phase, the cell duplicates its genetic material in preparation for cell division. After the S-phase, the cell proceeds to the G2 phase and subsequently enters mitosis (M-phase) or meiosis, where the replicated DNA is distributed to daughter cells.

VSAQ-9 : Name the stage of meiosis in which actual reduction in chromosome number occurs.

The actual reduction in chromosome number occurs during Anaphase I of meiosis. In Anaphase I, homologous chromosomes, each composed of two sister chromatids, separate from each other and move to opposite poles of the cell. This separation results in the reduction of the chromosome number by half in the daughter cells compared to the parent cell.